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Chemistry Paper 2 Flashcards

1
Q

What is the formula for calculating the rate of reaction in terms of reactant?

A

Mean rate of reaction = quantity of reactant used / time taken

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2
Q

What is the formula for calculating the rate of reaction in terms of product?

A

Mean rate of reaction = quantity of product formed / time taken

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3
Q

State the two units of measurement that reactants and products can be measured in.

A

By mass in grams or volume in cm3

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4
Q

What are the two possible units for rate of reaction?

A

g/s or cm³/s (where s is seconds)

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5
Q

What are the three possible units for rate of reaction?

A

g/s or cm³/s or mol/s (where s is seconds)

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6
Q

Susan carried out an experiment. 15g of product is made over 5 seconds. Calculate the rate of reaction.

A

15/5 = 3 g/s

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7
Q

Abdullah reacts magnesium with hydrochloric acid. The mass of the reactants decreases by 12.3 g over 3 seconds. Calculate the rate of reaction.

A

4.1 g/s

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8
Q

Natalie mixes two solutions together to produce a gas. 70cm3 of gas is produced in 3.5 seconds. Calculate the rate of reaction.

A

20 cm3/s

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9
Q

1 mol of gas is produced in 80 seconds when a solid is reacted with an acid. Calculate the rate of reaction.

A

0.0125 mol/s

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10
Q

State the 5 factors that affect the rates of chemical reactions.

A

1) Concentration of reactants in solutions
2) Pressure of reacting gases
3) The surface area of solid reactants
4) Temperature
5) Presence of catalysts

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11
Q

How does increasing the pressure of reacting gases affect the rate of reaction?

A

It increases.

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12
Q

How does decreasing the pressure of reacting gases affect the rate of reaction?

A

It decreases.

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13
Q

How does increasing the concentration of reactants in solution affect the rate of reaction?

A

It increases.

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14
Q

How does decreasing the concentration of reactants in solution affect the rate of reaction?

A

It decreases.

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15
Q

How does increasing temperature affect the rate of reaction?

A

It increases

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16
Q

How does decreasing temperature affect the rate of reaction?

A

It decreases.

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17
Q

How does increasing the surface area of solid reactants affect the rate of reaction?

A

It increases

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18
Q

How does decreasing the surface area of solid reactants affect the rate of reaction?

A

It decreases.

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19
Q

How does the presence of a catalyst affect the rate of reaction?

A

It increases

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20
Q

State the two conditions that need to be met in order for particles to react.

A

1) Particles must collide

2) They must collide with sufficient energy

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21
Q

Define activation energy.

A

The minimum amount of energy that particles must have to react.

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22
Q

Predict and explain the affect of increasing concentration on the rate of chemical reaction.

A

Reactions occur when particles collide with sufficient energy.
Increasing concentration means there are more particles in the same volume.
So there are more frequent collisions.
The rate of reaction increases.

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23
Q

Predict and explain the affect of increasing surface area on the rate of chemical reaction.

A

Reactions occur when particles collide with sufficient energy.
Increasing surface area exposes more particles.
So there are more frequent collisions.
The rate of reaction increases.

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24
Q

Predict and explain the affect of increasing temperature on the rate of chemical reaction.

A

Reactions occur when particles collide with sufficient energy.
When the temperature increases particles move faster with more energy.
There are more frequent collisions meeting the activation energy.
Rate of reaction increases.

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25
Q

Predict and explain the affect of decreasing pressure on the rate of chemical reaction.

A

Reactions occur when particles collide with sufficient energy.
Decreasing the pressure means less gas particles in the same volume.
So there are less frequent collisions.
The rate of reaction decreases.

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26
Q

What is a catalyst?

A

Something which changes the rate of a reaction but is not used up in that reaction

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27
Q

How do catalysts speed up reactions?

A

They provide a different route for the reaction to take place which has a lower activation energy.

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28
Q

The same catalyst can be used for many different reactions. True or false?

A

False.

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29
Q

What are enzymes?

A

Biological catalysts.

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30
Q

Many industrial processes use catalysts. Suggest why.

A

Catalysts provide a different route for the reaction to take place which has a lower activation energy.
Less energy is required.
Saves money.

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31
Q

How are reversible reactions different to reactions that go to completion?

A

In reversible reactions the product of the reaction can react to produce the original reactants.

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32
Q

By looking at a word or symbol equation, how can you determine if a reaction is a reversible reaction?

A

A reversible reaction will have a reversible arrow sign. ⇌

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33
Q

If a reaction is exothermic in the forward direction what will it be in the reverse direction?

A

Endothermic

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34
Q

Two reactants require 30kJ to turn into products. What energy transfer is involved when the products turn into reactants?

A

30kJ is released

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35
Q

What is equilibrium?

A

The point in a reversible reaction when the forward and reverse reactions are occurring at the same rate in a closed system.

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36
Q

How is the amount of reactant changing at equilibrium?

A

It is not changing

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37
Q

How is the amount of product changing at equilibrium?

A

It is not changing

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38
Q

What condition must be met in order for equilibrium to be established for a reversible reaction?

A

The reaction must take place in a closed system.

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39
Q

What is Le Chatelier’s principle?

A

When a reaction at equilibrium is changed, it will seek to counteract that change

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40
Q

N2(g) + 3H2(g) ⇌ 2NH3(g)
The above reaction occurs in a reaction mixture. Ammonia is removed from the reaction mixture. Explain the effect on the position of equilibrium.

A

Moves to the right hand side to produce ammonia.

To counteract the change.

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41
Q

2HCl(g) ⇌ H2(g) + Cl2(g)
The above reaction takes place in a reaction mixture. Hydrochloric acid is added to the reaction mixture. Explain the affect on the position of equilibrium.

A

Moves to the right hand side to produce hydrogen and chlorine.
To counteract the change.

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42
Q

2HCl(g) ⇌ H2(g) + Cl2(g)
The forward reaction is endothermic. Predict the effect of increasing the temperature on the amount of chlorine gas produced at equilibrium. Explain your answer using Le Chatelier’s Principle.

A

1) Amount of chlorine gas increases
2) Because system shifts to counteract the change
3) Because shifts to endothermic direction / shifts to take in energy

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43
Q

C2H4(g) + H2O(g) -> C2H5OH(g) ΔH = −45 kJ per mole
How would increasing the temperature change the YIELD of ethanol at equilibrium? Give a reason for your answer.

A

1) Increasing the temperature would lower the yield / equilibrium position moves to the left
2) Since the backwards reaction is endothermic / the forward reaction is exothermic

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44
Q

How does temperature affect the position of equilibrium?

A

Raising the energy of the system will shift it towards the endothermic reaction. Lowering it shifts it to the exothermic reaction.

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45
Q

C2H4(g) + H2O(g) -> C2H5OH(g) ΔH = −45 kJ per mole
How would increasing the pressure change the YIELD of ethanol at equilibrium? Give a reason for your answer.

A

1) Increasing the pressure would increase the yield / position of equilibrium moves to the right
2) Because the position moves in the direction of the lower number of moles of gas

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46
Q

2HCl(g) ⇌ H2(g) + Cl2(g)

Explain the effect of increasing the pressure on this equilibrium.

A

No change because there is an equal number of gas molecules on each side of the equation.

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47
Q

N2(g) + 3H2(g) ⇌ 2NH3(g)
The above reaction occurs in a reaction mixture. A low pressure is used in this reaction. Explain the effect on the yield of ammonia.

A

Decreases yield, because there are more moles/molecules of gas on the left hand side.

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48
Q

How does pressure affect the position of equilibrium?

A

Moves the position of equilibrium towards the side with less molecules.

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49
Q

What type of resource is crude oil?

A

It is a non-renewable finite resource.

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50
Q

What is crude oil made up of?

A

The remains of ancient biomass consisting mainly of plankton.

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51
Q

What is a finite resource?

A

One that will run out

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52
Q

Why is crude oil a finite resource?

A

Because we are using it faster than it is being produced.

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53
Q

What is a hydrocarbon?

A

A compound made of atoms of carbon and hydrogen only

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54
Q

Name the first four alkanes

A

Methane, ethane, propane, butane

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55
Q

What is the general formula for alkanes?

A

CnH2n+2

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56
Q

Most of the compounds in crude oil are what type of molecule?

A

Hydrocarbons

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57
Q

What is the formula of methane?

A

CH4

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58
Q

What is the formula for propane?

A

C3H8

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59
Q

Name the alkane with the formula C2H6

A

Ethane

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60
Q

Name the alkane with the formula C4H10

A

Butane

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61
Q

What is fractional distillation?

A

A process used to separate mixtures of substances with different boiling points

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62
Q

What are the steps involved in fractional distillation?

A

Crude oil is heated and vaporised.
Gas molecules rise up the fractionating column.
They condense at different points in the column as they have different boiling points.
Molecules with similar boiling points are separated within the same fraction.

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63
Q

The products of the fractional distillation of crude oil can be used for two main things. What are they?

A

1) Used as fuel

2) Feedstock for the petrochemical industry

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64
Q

Name four materials that are produced by the petrochemical industry.

A

Solvents, lubricants, polymers and detergents

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65
Q

Name five fuels we obtain from crude oil

A

Petrol, diesel, kerosene, heavy fuel oil and liquefied petroleum gases

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66
Q

What is a fuel?

A

A substance which when reacted with oxygen releases a large amount of energy

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67
Q

Complete the word equation: hydrocarbon + oxygen ->

A

hydrocarbon + oxygen -> carbon dioxide + water

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68
Q

During combustion, the carbon and hydrogen in hydrocarbons are reduced. True or False?

A

False, they are oxidised.

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69
Q

When does incomplete combustion occur?

A

When there is not enough oxygen present

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70
Q

How does boiling point change with the length of an alkane?

A

The longer the alkane, the higher its boiling point

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71
Q

How does viscosity change with the length of an alkane?

A

The longer the alkane, the more viscous (the thicker) it is

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72
Q

How does flammability change with the length of an alkane?

A

The longer the alkane, the less flammable it is

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73
Q

Write a balanced equation for the combustion of methane CH4

A

CH4 + 2O2 -> CO2 + 2H2O

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74
Q

What is cracking?

A

The process of breaking down a long hydrocarbon into smaller hydrocarbons

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75
Q

What are the products of cracking?

A

Short alkanes and alkenes

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76
Q

Why is cracking important?

A

Because it produces smaller hydrocarbons of which there is a greater demand because they are more useful than larger hydrocarbons.

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77
Q

How are alkenes different to alkanes?

A

Alkenes are more reactive than alkanes

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78
Q

How do you test for the presence of an alkene?

A

React with bromine water. Positive test will show colour change from bright orange to colourless.

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79
Q

What are alkenes used to produce?

A

Polymers.

80
Q

Describe the process of steam cracking.

A

The hydrocarbon is heated until it vaporises.
It is mixed with steam.
The mixture is heated to a very high temperature.
The long chain cracks to produce a smaller alkane and an alkene.

81
Q

Describe the process of catalytic cracking.

A

The hydrocarbon is heated until it vaporises.
It is passed over a hot powered aluminium oxide catalyst.
The long chain cracks to produce a smaller alkane and an alkene.

82
Q

Complete the equation to show the cracking of a large hydrocarbon. C23H48 -> C12H26 + ______

A

C23H48 -> C12H26 + C11H22

83
Q

Complete the equation to show the cracking of a large hydrocarbon. _________ -> C11H24 + C8H16

A

C19H40 -> C11H24 + C8H16

84
Q

In chemistry what is a “pure” substance?

A

A substance made of a single element or compound, not mixed with any other substances.

85
Q

Pure elements and compounds melt and boil at……

A

specific temperatures

86
Q

How can pure substances be distinguished from impure ones?

A

By their melting/boiling points

87
Q

Describe the melting and boiling points of impure substances

A

They change state at a range of temperatures

88
Q

Water boils at 100oC. When salt is added to water how does the boiling point of water change?

A

It increases and occurs over a range of temperatures.

89
Q

Ice melts at 0oC. When salt is added to ice how does the melting point change?

A

It lowers and occurs over a range of temperatures.

90
Q

In everyday language what is a “pure” substance?

A

A substance that has nothing added to it, so it is in its natural state.

91
Q

Considering how the word pure is used in everyday language, give an example of a pure substance.

A

Honey, milk etc…

92
Q

What is a formulation?

A

A mixture designed as a useful product

93
Q

Give three examples of formulations

A

fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.

94
Q

How are formulations made?

A

By mixing the components in in carefully measured quantities to ensure that the product ahs the required properties.

95
Q

What is chromatography?

A

A process to separate the constituents of a mixture

96
Q

In paper chromatography, what is the difference between the mobile phase and stationary phase?

A

Paper is stationary, solvent (usually water or ethanol) is mobile

97
Q

How can chromatography show the difference between pure and impure substances?

A

Pure substances will only produce a single spot.

98
Q

State the equation to calculate the Rf value.

A

Rf = distance moved by substance / distance moved by solvent

99
Q

A student carried out a chromatography practical. The solvent moved 110mm from the baseline. A yellow pigment moved 46mm from the baseline. Calculate the Rf value of the yellow pigment. Give your answer to 2 dp

A

0.42

100
Q

How would chromatography show that some food colourings are mixtures?

A

There would be more than 1 dot in a vertical line.

101
Q

From a chromatogram, how can you determine which substance is most soluble in the solvent used?

A

That substance will have travelled up the furthest and be closest to the solvent front.

102
Q

Why are substances in a mixtures separated out at different heights on a chromatogram?

A

Because they have different levels of attraction to the paper, and different solubility in the solvent

103
Q

Why is lid/watch glass placed over the beaker when carrying out a chromatography practical?

A

To stop the solvent from evaporating.

104
Q

What should you draw the baseline with and why?

A

A pencil so it doesn’t dissolve in the solvent.

105
Q

Different compounds have the same Rf values in different solvents. True or false?

A

False.

106
Q

How can hydrogen be tested for?

A

Makes a squeaky pop when a lighted splint is placed in it

107
Q

How can oxygen be tested for?

A

Relights a glowing splint

108
Q

How can carbon dioxide be tested for?

A

Bubble through limewater, turns it milky (cloudy)

109
Q

How can chlorine be tested for?

A

Bleaches damp litmus paper white

110
Q

For how long have the proportions of different gases in the atmosphere been the same as they are today?

A

200 million years

111
Q

What percentage of gas in the atmosphere is nitrogen?

A

Roughly 80%

112
Q

What percentage of gas in the atmosphere is oxygen?

A

Roughly 20%

113
Q

Other than nitrogen and oxygen, what other gases are present in the atmosphere?

A

Carbon dioxide, water vapour and noble gases.

114
Q

Why have theories about what was in the Earth’s early atmosphere changed and developed over time?

A

Because of the timescale of it being 4.6 billion years ago. No one was alive then.

115
Q

Fill in the blanks. One theory about the Earth’s early atmosphere states that during the first billion years of the Earth’s existence there was intense ___________ activity that released ________ that formed the early atmosphere.

A

volcanic, gases

116
Q

What gases do some scientists think were present in the Earth’s early atmosphere?

A

Carbon dioxide, water vapour, methane, ammonia and nitrogen

117
Q

How do some scientists think carbonate precipitates formed the sediments on the sea bed?

A

Carbon dioxide dissolved in the water of the oceans and through a series of chemical reactions produced carbonate precipitates that formed sediments on the sea bed.

118
Q

How do some scientists think the early oceans were formed?

A

The Earth cooled and some of the water vapour in the Earth’s atmosphere condensed to form the oceans.

119
Q

Which planets of today do some scientists think the Earth’s early atmosphere was like?

A

Mars and Venus

120
Q

State the word equation for photosynthesis.

A

Carbon dioxide + water -> glucose + oxygen (light above the arrow)

121
Q

State the balance symbol equation for photosynthesis.

A

6CO2 + 6H2O -> C6H12O6 + 6O2

122
Q

How did the amount of oxygen in the early atmosphere increase?

A

Algae first produced oxygen 2.7 billion years ago, they photosynthesised, increasing the amount of oxygen in the atmosphere.

123
Q

Apart from algae, which other organism can photosynthesise?

A

Green plants.

124
Q

When algae and plants photosynthesise, the decrease the amount of a certain gas in the atmosphere. Name this gas.

A

Carbon dioxide.

125
Q

During the evolution of the Earth’s early atmosphere, the amount of carbon dioxide decreased. State the two main ways in which it decreased.

A

1) Algae and plants photosynthesising

2) By the formation of sedimentary rocks and fossil fuels that contain carbon.

126
Q

Why are greenhouse gases essential to support life on Earth?

A

They maintain temperatures on Earth high enough to support life.

127
Q

State three greenhouse gases.

A

Water vapour, methane and carbon dioxide.

128
Q

Describe the greenhouse effect.

A

Short wavelength radiation from the sun passes through the atmosphere to the Earth’s surface, the Earth heats up and then cools emitting longer wavelength radiation. The greenhouse gas molecules absorb and re-radiate this in all directions including back down to Earth, heating the Earth.

129
Q

State two human activities that have increased the amounts of carbon dioxide in the Earth’s atmosphere.

A

Deforestation

Burning fossil fuels

130
Q

State two human activities that have increased the amounts of methane in the Earth’s atmosphere.

A

Agriculture - raising more cattle

Creating more waste - more landfill sites and agricultural waste

131
Q

Why are scientists concerned about the human activities that cause an increase in the amount of greenhouse gases in the atmosphere?

A

Scientists believe it will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change.

132
Q

The evidence for climate change has been peer-reviewed. Why is this important?

A

So that you know the information is reliable. Helps prevent false claims.

133
Q

Why is it difficult to fully understand the Earth’s climate?

A

Because the Earth’s climate is a complex system that is very difficult to model.

134
Q

It is very difficult for scientists to model the Earth’s climate. What problems can this lead to?

A

This can lead to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased.

135
Q

Complete the sentence: “An increase in average __________ ____________ is a major cause of climate ___________.”

A

Global temperature, change

136
Q

Describe the effect of global climate on rainfall patterns.

A

Changes in rainfall patterns may cause some regions to get too much or too little water.

137
Q

Describe the effect of global climate on sea levels.

A

Increase in global temperatures could lead to polar ice caps melting - causing a rise in sea levels, increasing flooding in coastal areas and coastal erosion.

138
Q

Describe the effect of global climate on storms.

A

The frequency and severity of storms may increase.

139
Q

Describe the effect of global climate on water availability.

A

Changes in temperature and the amount of water available in a habitat may affect wild species leading to differences in their distribution.

140
Q

Define carbon footprint.

A

The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

141
Q

Complete the sentence: “The carbon footprint can be ____________ by reducing ________________ of carbon ______________ and methane.”

A

Reduced, emission, dioxide

142
Q

What alternative fuels could be used instead of fossil fuels to reduce carbon footprints?

A

Renewable energy resources or nuclear energy.

143
Q

Describe two ways in which governments can help reduce carbon footprints.

A

1) Governments could tax companies or individuals based on the amount of greenhouse gases they emit.
2) Government could put caps on emissions of all greenhouse gases that companies make - then sell licences for emissions up to that cap.

144
Q

How can carbon capture help reduce carbon footprints?

A

Carbon dioxide produced can be ‘captured’ and stored deep underground in cracks in the rock such as old oil wells.

145
Q

Why might companies review the processes they use to reduce carbon footprints?

A

They may review them to explore more efficient processes that cut waste reduce greenhouse gas emissions.

146
Q

State two reasons why reducing greenhouse gas emissions may be limited.

A

1) A lot of work needs to be done developing alternative technologies that result in less emissions - costly.
2) Governments may be worried that making changes will have a negative impact on economic growth.
3) It is difficult to make international agreements on reducing greenhouse gas emissions when not everyone is on board.

147
Q

State a major source of atmospheric pollutants.

A

The combustion of fuels.

148
Q

Complete the sentence: “Most fuels, including coal, contain _______ and/or hydrogen and may also contain some ____________.”

A

Carbon, sulphur

149
Q

How can sulphur dioxide be produced?

A

From the combustion of fossil fuels containing sulphur impurities.

150
Q

How can nitrogen oxides be produced?

A

By the reaction of nitrogen and oxygen in air, caused by the heat of burning in the internal combustion engines of cars. (Very high temperatures)

151
Q

Explain how soot (carbon particulates) can form.

A

The incomplete combustion of fuel because not enough oxygen is present.

152
Q

Write a balanced equation for the production of nitrogen dioxide from nitrogen and oxygen.

A

N2+ 2O2–> 2NO2

153
Q

Sulphur dioxide is dissolved in water. What colour is universal indicator in a solution of sulphur dioxide?

A

Red/Orange/Yellow

154
Q

The incomplete combustion of fossil fuels produces carbon monoxide. What problems can carbon monoxide cause?

A

Carbon monoxide binds to haemoglobin which stops oxygen from binding.
This means less oxygen is able to be transported around the body.
A lack of oxygen can lead to fainting, a coma or even death.

155
Q

The incomplete combustion of fossil fuels can produce carbon soot (particulates). What problems do these particulates cause?

A

1) If inhaled they can cause damage to the lungs leading to respiratory problems.
2) They are also bad for the environment and can cause global dimming.

156
Q

Sulphur dioxide and oxides of nitrogen can cause harm to the environment. Explain how.

A

These gases can mix with clouds to form dilute sulphuric and nitric acid. This falls as acid rain and can kill plants and damage buildings and statues.

157
Q

Sulphur dioxide and oxides of nitrogen can cause harm to humans, why?

A

They can cause respiratory problems if breathed in.

158
Q

Give one advantage of reducing emissions of oxides of nitrogen.

A

Less acid rain or fewer respiratory problems in humans.

159
Q

True or false - Sulphur dioxide causes global dimming.

A

False.

160
Q

Why is carbon monoxide very difficult to detect?

A

It is a colourless, odourless, tasteless gas. It is very hard to detect.

161
Q

Where do humans obtain natural resources from?

A

The Earth, sea and air.

162
Q

Name the four things human use the Earth’s resources to provide:

A

Warmth, shelter, food and transport.

163
Q

Complete the sentence: “Natural resources, supplemented by ________________, provide food, timber, clothing and fuels.

A

Agriculture

164
Q

Define sustainable development.

A

Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.

165
Q

What does synthetic mean?

A

Man made.

166
Q

What is meant by a renewable resource?

A

A resource that is being made as fast as it is used up.

167
Q

What is meant by a non-renewable resource?

A

A finite resource, that is being used up faster than it is being made.

168
Q

Give 2 examples of finite resources.

A

Fossil fuels (coal, oil and gas) and nuclear fuels (plutonium and uranium).

169
Q

State 2 examples of natural products that are supplemented or replace by agricultural and synthetic products.

A

1) Rubber can be replace by synthetic polymers.

2) Fertilisers can be used to produce a high yield of crops.

170
Q

Define potable water.

A

Water that is safe to drink.

171
Q

Explain why potable water is not pure.

A

Because it contains small amounts of dissolved substances.

172
Q

Which two factors will determine the way in which potable water is produced?

A

1) The available supply of water

2) Local conditions

173
Q

Define freshwater.

A

Naturally occurring water with a small amount of dissolved substances.

174
Q

Describe how potable water is produced in the UK.

A

1) Choosing an appropriate source of fresh water e.g. lake
2) Pass the water through filter beds to remove large solid bits
3) Sterilise the water - this can include using chlorine, ozone or ultraviolet light.

175
Q

If supplied of freshwater are limited, what other method can be used to produced potable water?

A

Desalination of salty water or sea water.

176
Q

State the two methods used to produce potable water from seawater.

A

1) Distillation

2) By processes that use membranes such as reverse osmosis.

177
Q

Describe the difference in energy demand of producing potable water from sea water instead of fresh water.

A

The two methods that produce potable water from sea water require a large amount of energy.

178
Q

Describe three places where waste water can come from.

A

1) Sewage from domestic sources
2) Agricultural systems
3) Industrial processes

179
Q

Why must waste water be treated before being released back into the environment?

A

So that the environment isn’t polluted - waste water can cause harm to wildlife.

180
Q

State the 4 steps involved in sewage treatment.

A

1) Screening and grit removal
2) Sedimentation to produce sewage sludge and effluent
3) Anaerobic digestion of sewage sludge
4) Aerobic biological treatment of effluent

181
Q

State the two products of the anaerobic digestion of sewage sludge.

A

Natural gas and fertiliser.

182
Q

What additional treatments may be required for waste water containing toxic substances?

A

1) Adding chemicals to precipitate metals
2) UV radiation
3) Using membranes

183
Q

Is copper a finite or renewable resource?

A

Finite.

184
Q

Describe how copper can be extracted from low-grade ore by phytomining.

A

1) Plants are grown in soil that contains copper
2) Copper gradually builds up in the leaves
3) The plants can are harvested, dried and burned in a furnace.
4) The ash contains soluble copper compounds that can be extracted by electrolysis or displacement with a more reactive metal e.g. scrap iron.

185
Q

Describe how copper can be extracted from low-grade ore by bioleaching.

A

1) Bacteria are used to convert copper compounds into soluble copper compounds, separating the copper from the ore in the process
2) The leachate (the solution produced by the process) contains copper ions, which can be extracted by electrolysis or displacement with a more reactive metal e.g. scrap iron.

186
Q

Why are Life Cycle Assessments carried out for?

A

To look at the environmental impact at every stage of a product’s life.

187
Q

State the four stages of a products life.

A

1) Extracting and processing raw materials
2) Manufacturing and packaging
3) Use and operation during its lifetime
4) Disposal at the end of its life, including transport and distribution at each stage

188
Q

Describe how extracting and processing raw materials can have an impact on the environment.

A

1) Extracting raw material can damage the local environment e.g. mining.
2) Raw materials often need processing which requires large amounts of energy - burning fossil fuels produces greenhouse gases.

189
Q

Describe how manufacturing and packaging of an item can have an impact on the environment.

A

1) Often requires a large amount of energy - burning fossil fuels produces greenhouse gases.
2) Some processes at can produce waste products that need to be disposed of. These can pollute the environment and cause damage to plants and wildlife.

190
Q

Describe how using a product can have an impact on the environment.

A

1) The product may run on fuel. Burning fossil fuels produces greenhouse gases.
2) Fertilisers can leach into streams causing damage to ecosystems.

191
Q

Describe why LCAs are not a purely objective process.

A

Allocating numbers to pollutants effects is difficult and would require a judgement based on the person’s values. This means LCAs can be biased.

192
Q

State two ways in which we can reduce the use of limited resources.

A

1) Reuse products

2) Recycle materials

193
Q

Why might the extraction and processing of resources be unsustainable?

A

Because the processes require large amounts of energy - obtained from finite resources.

194
Q

State one way in which chemists can reduce the energy demand industrial processes.

A

By using catalysts.

195
Q

How is glass recycled?

A

Glass bottle are crushed and melted to make different glass products.

196
Q

How are metals recycled?

A

Metals can are melted and recast or reformed into different products.

197
Q

The amount of separation required for recycling depends on the material and the properties required for the final product. Give an example of this.

A

Waste steel and iron can be kept together as they can both be added to iron in a blast furnace to reduce the amount of iron ore required.

LST (6 decks)

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